Recovery of sugar from molasses



April 22, 1941.

R. H. COTTRELL ETIAL 2,239,082 gEcovERY 0F SUGAR mom MOLASSES Original Filed Oct. 27, 1936 WATER 2 K y 4 P MOLASSES I/ SE CO-LD PRECIPITATIONfI $TEAML- WARMING,

WARM

WATER I v WARM FILTRATION 1 43 I I HOT PRECIPITATION STEAM HOT THICKENING WARM CAKE HOT WASTE To CARBONATION INVENTOK.

ATTORNEY.

Patented Apr. 22, 1941 UNITED STATES PATENT OFFICE 2,229,082 RECOVERY or SUGAR. FROM MOLASSES Roy H. Cottrell and Vernal Jensen, Ogden, Utah Original application October 27, 1936, Serial-No.

107,794. Divided and t 1939, Serial No. 277,983

8 Claims.

Another object is to provide an improved method for recovering sucrose from molasses which is' more eiiicient and economical than those heretoiore practised, and, at the same time, which may be carried out by the use of less apparatus equipment than has heretofore been possible.

Another object is to efi'ect the recovery of a larger proportion of sugar in marketable form than has heretofore been accomplished.

A still further. object oi the invention is to provide a method wherein all of the above advantages are realized and in which a lesser quantity of lime is required to recover a unit weight of sugar.

In a general way the Stefi'en process, as heretofore practised, comprises two groups of steps. The first of these includes the precipitation of socalled cold saccharate and its subsequent sepa-' ration, as by filtration, from its cold-motherliquor. The second includes the precipitation of so-called hot saccharate from the cold motherliquor resulting from the first separation step and the subsequent separation, as by filtration or decantation and filtration, of the hot saccharate from its hot mother-liquor, commonly termed hot waste liquor, which is discarded from the system substantially devoid of sucrose content.

In practising the Stefienizing operation it is application June 8,

from 12 to 17 C.. The resulting mixture of precipitated cold calcium saccharate and motherliquor, frequently termed solution from cooler or finished cooler solution, having a temperature substantially within the range of from 12 to 17 C., is subjected to a separation operation, as by filtration, so as to produce a filter-cake containing the precipitated cold calcium saccharate which, after washing with cold water; is largely free from mother-liquor, and a solution substantially tree from suspended precipitate, sometimes referred to as cold waste water, which is subjected to further treatment as hereinafter described. The cold water waste irom the foregoing group of steps usually contains substantially .5% on solution, of sucrose and an alkalinity equal to substantially .7 gm. of CaO per 100 cc. of solution. Customarily it is heated to a temperature of from 85 to 87 C. With the result that a second precipitate of calcium saccharate, usually termed hot saccharate precipitates, is formed. The resulting mixture of hot precipitate and hot mother-liquor is then subjected to a separation 'operation, as by filtration or decantation and fil- 5 tration, the temperature being maintained withcustomary to dilute the molasses, which usually contain approximately sucrose and 83% total dry substance, with water to produce a solution containing substantially 5% to 8% sucrose frequently referred to as solution for cooler. The temperature of this solution is then lowered to a point within the range of'substantially from 12 to 17 C. The temperature having been thus adjusted, powdered quickl me (CaO), substantially all minus 200 mesh. is added to thesolution in incremental amounts up to a total sul'ilcient to precipitate substantially 90% of the sucrose con.- tent of the mixture. During the addition of lime the mixture is maintained in a state of agitation and its temperature is kept within the range of in the range of substantially from to 87 C. This operation produces a sugar-containing hot saccharate filter-cake which is washed with warm water so that it is substantially free of motherliquor, and a filtrate comprised of the hot motherliquor or, as it is sometimes termed, hot waste water, The liquid is now substantially exhausted of recoverable sucrose content and is discarded from the system.

The foregoing describes the Steffen process as it is generally practised where both groups of steps, the cold precipitation and the hot precipitation, are carried out. Some installations dispense with or are not equipped for the hot precipitation stage and run the cold waste water to sewer, perhaps using part of it for diluting the original molasses. In that event the major part of the""s'ucrose content of the cold waste, of course, is lost.

In connection with the cold precipitation stage if the precipitation were effected at temperatures below the hereinbefore prescribed range, 1. e., below 12 0., less reagent (CaO) would be required but a less eflective separation would result. This may be due to the fact that the higher viscosity 01' the mixture makes it difilcult to filter, or to otherreasons not readily understood. Furthermore, if the precipitation were efi'ected at temperatures in excess of the i. e. above 17 0., a more effective separation is prescribed range,

of the hot sludge will raise the attainable but more reagent (CaO) is required. The specified temperature range, therefore, representsthe conditions under which the operation is most economically effected.

In practising the hot precipitation process of the Steiiens operation if the cold waste water is not heated to temperatures above substantially 85 C. a maximum of precipitate will not be produced. Furthermore, if the mixture, having been sufliciently heated to obtain a satisfactory precipitate, be allowed to cool to temperatures below substantially 85 C, there occurs a dissolution of precipitate with a corresponding lessening of efiiciency.

The present invention, in addition to simplifying the above described Steffenizing operations, accomplishes some of its objects in the following general manner. saccharate precipitates, according to an embodiment of this invention, the cold precipitation is effected at temperatures below substantially 12 C., thereby obtaining a desired precipitation of cold saccharate and, at the same time, making possible a material reduction in the amount of lime required over former practice. Thereafter the separation, as by filtration, is effected at temperatures in excess of the generally prescribed range, 1. e. above substantially 17 0., thereby obtaining a more effective separation. It is found that filtration in the range above 17 C. yields a filter-cake containing less impurities per pound of sugar in the cake, and this necessarily yields an increase in the proportion of sugar recovered in marketable form. Contrary to general belief it is discovered, as a part of this invention, that heating the mixture of cold saccharate precipitate and cold motherliquor to filter it at temperatures above the normally prescribed range does not cause a dissolution of the precipitate or exert any deleterious effect whatever.

Still further advantages of the present invention are realized in a system for the, recovery of both the cold and hot precipitates. In this embodiment the hot saccharate precipitate, in the form of a thickened sludge, is added to the finished cooler solution, 1. e. the mixture of cold precipitate and cold mother-liquor. The: heat temperature of the resulting mixture to that desired, which is above substantially 17 C. and the mixture is then filtered obtaining a cake composed of both In the recovery of cold quantity of hot the cold and hot calcium saccharate precipitates,

thus eliminating the usual step of separately filtering the hot precipitate. The filtrate from this filtration step is a solution which is substantially free from suspended precipitate but which contains substantially .5 gm. of sucrose and an alkalinity equivalent to substantially .7 gm. of 09.0 per 100 cc. This solution is heated, as hereinbefore described, to precipitate the hot calcium saccharate. The resulting mixture is subjected to a thickening operation, as by decantation, to obtain a sludge comprising all ofthe hot precipitate and a portion of the hot motherliquor which sludge is added to the finished cooler solution as above described, and a hot waste water substantially free of suspended precipitate and practically exhausted of recoverable sucrose content, which waste water is discharged from the system.

The present invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following detailed description. In the accompa y s drawing, which is 1y indicating a system by which the invention may be practised, for the purpose of example there has been illustrated the best embodiment of the invention now known to us, but such embodiment is to be regarded as typical only of many possible embodiments, and the invention is not to be limited thereto.

Referring to the drawing, according to the preferred form of the invention sugar-beet molasses, indicated at I, of substantially the composition previously described, i. e. of a density ofabout to Brix, is diluted with water from the supply 2 to produce a solution containing substantially 5 to 6 gms. of sucrose per 100 cc. of solution. The temperature of this solution is then adjusted to a point within the range of from 5 to 8 C. in a cold precipitation zone 3. To the cold solution powdered qulcklime (CaO), substantially all minus 200 mesh, from a source 4, is added in incremental amounts up to a total suflicient to precipitate of the sucrose content of the mixture. During this operation the mixture is maintained in a state of agitation and at a temperature substantially within the above mentioned range of from 5 to 8 C. The precipitation having been effected as just described, the amount of quicklime required per pound of sucrose precipitated will be found to be less than that usually required in past practise.

The above described cold precipitation reaction having been completed, the resulting cold saccharate mixture 5, comprising cold calcium saccharate precipitate'and cold mother-liquor and having a temperature of from 6 to 10 0., is mixed in a warming zone 6 with a thickened sludge obtained, as ,via the flow-path I, from a subsequent operation. This temperature of substantially 80 C., is composed of hot saccharate precipitate suspended in a mother-liquor and isadded to the cold saccharate mixture in the proportion of approximately or four volumes of the cold mixture to produce a filter-feed mixture 8 having a temperature of substantially from 30 to 35 C. .In the event that the temperature of the mixture of the two productsi. e. the filter-feed 8, is, for any reason,

below the prescribed range, or if a temperature above the preferred range be desirable, the temperature of said filter-feed mixture may be adjusted by the direct introduction of steam-thereinto, as indicated at 9, or by the application of other suitable heating medium.

The filter-feed mixture 8 containing both the cold and the hot saccharate precipitates, itst'emperature having been adjusted as above described, is now subjected to separation by filtration, preferably in a rotary vacuum filter of the Oliver type indicated diagrammatically at N. This operation produces a filter-cake, shown leaving the filtration stage, along the path H, comprising a mixture of cold and hot calcium saccharate precipitates. In the filtration stage the cake is washed with warm water, preferably having a temperature of from 30 to'55 C., from the source l2. The warm wash water, it is found, exerts a moving from the cake occluded mother-liquor and non-sugar impurities, so that the filter-cake recovered from the system along the path ll willv contain calcium saccharate of high purity which will yield an increased portion of its sucrose content in the form of marketable sugar.

a' flow-sheet diagrammaticalsludge, having a one volume of sludge to three highly eihcient cleansing action in.re-'

The filtrate mother-liquor, from the above described separation substantially free from suspended solids, containing (in solution) substanis conducted along the path it to a hot precipitation zone ll. In this zone the filtrate motherliquor is heated to a temperature of substantially from 83 to 87 C. by the injection of steam thereinto from the source l5, or by the application thereto of other suitable heating medium. Such heating causes the precipitation of approximately 90% o! the sucrose content of the filtrate mother-liquor in the form of hot calcium saccharate precipitate to produce a hot mixture of said precipitate suspended in hot mother-liquor.

Upon completion of the hot precipitation reaction the hot mixture leaves the hot precipitation zone It and is conducted along the path it to a hot thickening stage I! wherein it is subiected to separation as by decantation thickening, care being taken to avoid loss of temperature. The thickening operation which is preferably carried out in a Dorr tray thickener. produces a hot slurry composed of substantially all of the hot saccharate precipitate and approximately one-fourth of the hot mother-liquor present in the hot mixture, and a hot waste liquor amounting to approximately three-fourths of the hot mother-liquor, which waste liquor is substantially free from suspended precipitate and which seldom containsin solution more than .05 gm. of sucrose per 100 cc. The hot waste liquor is discarded from the process, as indicated in the drawing at I8, substantially stripped of recovteed mixture I in a subsequent cycle of the process, as hereinbefore described. By eflecting the separation with decantation thickening and returning the hot calcium saccharate sludge to be filtered together with the cold calcium saccharate the costly step, customarily used in past practise, oi finally separately filtering the hot sludge to form a washed hot saccharate filtercake, as such, is eliminated and the process simplified accordingly, since the filters customarily used to separate the cold saccharate precipitate inpast practise have ample capacity for separating the mixed precipitates provided for in the present invention. Contrary to previously heldchemical. views it is found, as a part of this invention, that in the mixing of the hotsaccharate slurry with the cold saccharate mixture in the herelnbeiore described warming step, the consequent substantial lowering of the temperature of the hot slurry does not operate to eflect dissolution oi -the hot saccharate precipitate. As was .hel'einbeiore mentione'd, it is known that ii the mixture of hot saccharate precipitate suspended in its own mother-liquor be cooled to points below 80 C. dissolution or the precipitate occurs. In such cases the calcium saccharate precipitate decomposes, the sucrose goes back into solution and most or the 30.0 is converted into calcium hydrate (MOE);- Thcrestter no amount of heating will effect the reprecipitation 01' all of the decomposed saccharate. In mixing the hot saccharate slurry with the cold saccharate mixture, as taught by the present invention, this dissolution is not experienced. The reason for this is not well understood, but one possible explanation resides in the hypothesis that, since the solution phase of the filter-feed mixture resulting from the warming step contains an alkalinity equivalent to .7 gm; of CaO and a sucrose content equivalent to .5 gm. per cc., the hot saccharate precipitate does not decompose, when suspended in it at temperatures of from 30 to 35 C., as would be the case were it cooled to a like temperature in its own mother-liquor which contains an alkalinity equivalent to approximately .4 gm. of 09.0 and a" sucrose content equivalent to .05 gm. per 100 cc.

Thus it will be seen that there are numerous advantages fiowing from the use of the present invention. Lower temperatures with consequent saving of lime are possible in the cold precipitation stage. Better separation is eflected through filtering at higher temperatures. The heat of the returned hot saccharate sludge is utilized to adJust the temperature of the filter-feed mixture, so that rarely is any additional heating equipment necessary. And of prime importance, the cold and hot saccharates are filtered together in one step, thus eliminating the customary hot filters and thereby effecting a considerable economy in equipment, space, labor and power consumption, and at the same time, as hereinbefore explained, obtaining an increase in the proportion of marketable sugar recovered.

li't'hiie the greatest operating economies and the highest sugar yield have been found to be achieved by the present. process, when carried out according to the hereinbefore set forth specific temperature ranges, it will be appreciated that the invention is not limited to these preferred conditions, but comprises broadly the novel step of returning hot calcium saccharate to the coldsaccharate mixture and filtering the two precipitates in a single operation, thus eliminating the heretofore necessary step of separately filtering the hot precipitate. Thus, in a broad aspect of the invention, the first step, namely, that of reacting lime with the sugar in the liquid aqueous solution 'of beet molasses, may be accomplished while maintaining the temperature of the reacting mixtures not above substantially 35 C., which represents approximately the known upper temperature limit up to which the cold reaction is satisfactorily operable. To the mixture resulting from this reaction, the hot calcium saccharate precipitate, preferably in the form of a thickened sludge'and obtained from the subsequent hot precipitation step, is added and the resulting mixture of hot and cold precipitates is filtered in a single operation and a filter cake obtained which contains both the cold and hot precipitates. The filtrate from this step is then heated according to the known procedure to a temperature suflicient to precipitate hot calcium saccharate. This precipitate is then returned and added to the mixture resulting from the cold precipitation step as previously mentioned, preferably after having had a'quantity of the hot mother-liquor removed by athickening operation.

In some instances it may be desirable to recover only the cold saccharate precipitate, discharging to waste the mother-liquor therefrom, and not carry out the hot saccharate precipitation steps. One aspect of the present invention is particularly applicable to an operation of that type. According to this aspect the molasses l are diluted with water from the supply 2 to form a solution containing substantially 5 to 6 gms. of sucrose per 100 cc. of solution. The temperature of the solution is then adjusted to within the range from 5 to 8 C., in the cold precipitation zone 3,

and maintained in that range while powdered quicklime (CaO) from the source 4 is added in incremental amounts up'to the desired total, agihereof, that warm water, within substantially the temperature range indicated, may be used for washing the filter-cake produced by cold-filtering the cold saccharate mixture in the cold filtering tation of the mass being provided the while, all

substantially as hereinbefore described. After the cold precipitation reaction is completed the .resulting mixture of cold saccharate precipitate and cold mother-liquor, having a temperature of from 6 to 10 C., is conducted along the path 5 to the warming zone 6 wherein it is heated to a temperature of substantially from 30 to 35 C. by

the direct introduction of steam thereinto' from the supply 9, or bythe application thereto of other suitable heating medium. In this phase of the invention, there being no hot precipitation 1 steps, there is no hot saccharate sludge mixed with the cold saccharate precipitate mixture. The warm mixture passes from the warming zone along the path 8 as filter-feed for the filtration stage It and comprises the cold saccharate precipitate suspended inits' mother-liquor and has a temperature of substantially from to C.,

In the filtration stage a separation is effected obtaining a filter-cake, recovered from the system via the path ll, containing the cold calcium saccharate precipitate which, after washing with warm water, preferably having a temperaturefrom 30 to55f C. from the source I2, is substantially free from mother-liquor. The filtrate mother-liquor from this separation leaves the filtration stage viaithe path l3 and, no further treatment of this liquor being contemplated; it is discharged to waste instead of being conducted to the hot precipitation zone as in a previously described form of the invention.

' tion operation, as by filtration,'to. produce a'filterstep of the customary Steffen procedure, and will result in improved washing efficiency, producing a cake which is freer of occluded motherliquor and non-sugar impurities. In. customary Steffen practise the cold saccharate mixture is filtered at temperatures of from 12 to 17 C. and the cake washed with water at substantially the same temperatures. Contrary to previously held views, it is found that this cake, produced by filtering at low temperatures; may be washed with warm water at temperatures of from 30- to 55 C. and there will be no dissolution of the saccharate precipitate, and an improved wash will be experienced. V

In any form of the, invention' the filter-cake recovered from the process via the path H is subsequently treated by known procedure for the recovery of sugar in a crystalline, marketable form. The cake is mixed with'water. to form a slurry which is then, treated with carbon-dioxide gas, resulting in the formation of precipitated calcium carbonate suspendedin a solution of sucrose. This mixture is subjected-to a separacake comprising the calcium carbonate washed substantially free of sugar and a filtrate comprising a clear sugar solution. The calcium carbon- 'ate filter-cake is discarded from the system and the sugar solution is concentrated, as by evapora- The modification of the invention just described makes possible decided advantages and economiesin those installations practising only cold precipitation. In past practise it was considereil impossible to realize the advantages of warm filtration coincidentally with the advantages to be obtained through cold -(6 C.) precipitation. Such of the process chemistry as was known seemed to preclude such a possibility. It

is found, however, as a part of this invention,

that heating the mixture of cold precipitate and cold mother-liquor to temperatures of from 30 to 35 C. does not cause dissolution of the precipitate and does not seem to have any deleterious efiect upon the same. This invention, therefore,

makes it possible to effect a considerable saving in lime by conducting the precipitation at lower temperatures than those heretofore customarily ployed, and to obtain a more effective separat io those heretofore customarily used.

Another feature of the present invention of by filtering at temperatures higher thansaccharate filter-cake.

.tiorrof its water content, and it's sucrose content largely recovered by means of crystallization. This operation yields a crystalline, marketable sugar and a final molasses containing such impurities as were present in the washed calcium pound of impurities in this cake will preventthe crystallization of one and one-half pounds of sucrose. Therefore, the greater the impurity content of the saccharate cake, the greater will be the amount of'sugar lost in the final molasses. The present invention, in all of its forms, re-

ducesthis loss by producing, as hereinbefore'explained, a calcium saccharate filter-cake having a minimum impurity content.

While herein has been shown and described a 6 system comprising a specific arrangement and kind of apparatus elements, and specific examples of methods of producingv a desired product.

it is to be understood that the invention is not limited to such specific system and methodsbut contemplates all such variants thereof as fairly fall within the scope of the appended claims.

The present application is a division of our previously filed application Serial No. 107,794, filed October 2'7, 1936. The foregoing is a com plete and exact duplicate of the specification of our said parent application.

Whatisclaimedis: 1. In a method of recovering sucrose from sugar-beet molasses, the steps of adding lime to the molasses while within a temperature. range of substantially from 5 to 12 C. tozprecipitatecalcium saccharate, adding sludge obtained from a subsequent step in the metho'dand containing hot calcium saccharate precipitateto the resulting mixture of cold calcium saccharate precipitate coldmother-liquor, filtering the resulting mixture while within a temperature-range of substantially from 30 to 35 C. to obtain a fi1tercake containing cold and hot calcium saccharate precipitates, heating the filtrate from said filtra-- tion step to precipitate hot calcium saccharate,

In general terms, one

treating the resulting mixture of hot calcium saccharate precipitate and hot mother-liquor to separate the same into a sludge containing the hot calcium saccharate precipitate and a substantially clearhot waste liquor, and adding said sludge to the mixture of cold calcium saccharate precipitate and cold mother-liquor in a previously-described step of the method.

2. In a method of recovering sucrose from sugar-beet molasses, the steps 01' adding lime to the molasses while within a temperature range of substantially from 5 to 12 C. to precipitate tates, heating the filtrate from said filtration step to precipitate hot calcium saccharate, treating tne resulting rmxture of hot calcium saccharate precipitate and hot mother-liquor to separate the same into a relatively hot sludge containing the hot calcium saccharate precipitate and a,

substantially clear hot waste liquor, and adding said sludge to the mixture of cold calcium saccharate precipitate and cold mother-liquor in a previously-described step of the method.

3. In a method of recovering sucrose from sugar-beet molasses, the steps of adding lime to the molasses while at a emperature below substantially 17 C. to precipitate calcium saccharate, adding sludge obtained from a subsequent step in the method'and having a temperature of substantially 80 C. and containing hot calcium saccharate precipitate to the resulting mixture of cold calcium saccharate precipitate and cold mother-liquor to form a filter-feed mixture having a temperature above substantially 17 C., filteringl said filter-feed mixture while at a temperature above substantially 17 C. to obtain a filter-cake containing cold and hot calcium saccharate precipitates, heating the filtrate from said filtration step to precipitate not calcium'saccharate, treating the resulting'mixture of hot calcium saccharate precipitate andhot motherliquor to separate the same into a sludge having a temperature of substantially 80 C. and containing the hot calcium saccharate precipitate and a substantially clear hot waste liquor, and adding said sludge to the mixture of cold calcium saccharate precipitate and cold mother-liquor in a previously-described step of the method.

4. In at method of recovering sucrose from sugar-beet molasses, the steps of adding lime to the molasses while within a temperature range of substantially from 5 to 12 C. toprecipitate calcium saccharate, adding sludge obtained from a subsequent step .in the method and having a temperature of substantially 80 C. and containing hot calcium saccharate precipitate to the resultingmixture of cold calcium saccharate precipitate and cold mother-liquor to form a filterfeedhaving a temperature oi substantially from to C., filtering said filter-feed mixture while within substantially said temperature range to obtain a'filter-cake containing cold and hot calcium saccharate precipitates,-heating the filtrate from said filtration step to precipitate hot calcium saccharate, treating the resulting mixture of hot calcium saccharate precipitate and hot mother-liquor to separate the same into a sludge having a temperature of substantially C. and containing the hot calcium saccharate precipitate and a substantially clear hot waste liquor, and adding said sludge to the mixture of cold calcium saccharate precipitate and cold mother-liquor in a previously-described step of the method.

5. In a process for recovering sucrose from sugar-beet molasses in which a molasses solution while at a temperature not above substantially 35 C. is treated with lime to precipitate calcium saccharate and thus form a mixture of cold calcium saccharate precipitate and cold mother-liquor, the precipitate separated from its mother-liquor by filtration, and the motherliquor heated to precipitate hot calcium saccharate; the improvement which comprises adding hot calcium saccharate precipitate obtained from the last mentioned step in the process to the mixture of cold calcium saccharate precipitate and cold mother-liquor, filtering the resulting mixture to obtain a filter-cake composed of both cold and hot calcium saccharate precipitates and a filtrate, heating the filtrate to a temperature suificientto precipitate hot calcium saccharate, and adding the hot precipitate to the mixture of cold precipitate andcold motherliquor in a previously described step in the process.

6. In a process of recovering sugar from a liquid aqueous solution of beet molasses, the steps of reacting lime with the sugar in the solution while maintaining the temperature of the reacting mixture not above substantially 35 C., adding hot calcium saccharate precipitate obtained from a subsequent step in the process to the mixture resulting from said reaction, filtering the subsequent step in the process to the resulting mixture of cold precipitate and cold motherliquor, filtering the resulting mixture to obtain a filter-cake composed of cold and hot calcium saccharate precipitates and a filtrate, heating the filtrate to a temperature sufiicient to precipitate hot calcium saccharate, and adding the hot precipitate to the mixture of cold precipitate and cold mother-liquor in a previously mentioned step in the process. i

8. The process of recovering sugar from a liquid aqueous'solution of beet molasses which comprises precipitating cold calcium saccharate by reacting lime with sugar; in the solution while maintaining the temperature of the reacting mixture not above substantially 35 C., adding hot calcium saccharate precipitate in the form of a thickened sludge and obtainedfr m a subsequent step in the process to the resulting mixture of cold precipitate and cold mother-liquor, filtering the resulting mixture to obtain a filter-cake composed of cold and hot calcium saccharate precipidiscarding the hot waste liquor from the process, tates and a filtrate, heating the flitrateto a temand adding the sludge to the mixture of cold preperature sumcient to precipitate hot calcium saccipitate and cold mother-liquor in a previously charate, separating the resulting mixture of hot mentioned step in the process.

calcium saccharate precipitate and hot motherliquor into a sludge containing the hot precipi- ROY H. COTIRELL. tate and a substantially clear hot waste liquor, VERNAL JENSEN. 

